1. Field of the Invention
The invention relates to a device for application in the sterile area for controlling an electric instrument provided in the non-sterile area, with the sterile area being separated from the non-sterile area substantially by a sheet-like covering means.
2. Description of the Prior Art
When surgical operations are performed on both the human body and an animal body, instruments driven by electromotor force are required to an ever-increasing extent for the purposes of assisting the surgical operation and for monitoring the operation, such as holding and positioning mechanisms of a tripod- or support-like configuration for endo-surgical instruments as well as for optical monitoring and recording units such as video cameras. For reasons of easier handling and for avoidance of monotonous long-lasting positioning operations such as optical endoscope viewing systems to which a video camera unit is connected, the surgeon mostly places the system in a position ideal for performance of the operation via an appropriate positioning mechanism with electromotor support. Such a motor-drive fixing device or positioning device is described in the German Patent DE 199 50 440.
In alt known electrically controllable devices serving for assistance in surgery, which the staff must operate, the fundamental problem of operability arises, specifically as the surgeon involved in the surgical operation works with both hands in the sterile area.
When surgical operations are performed on a patient, the sterile area is limited by the clinical covering sheet lying on the patient, which consists normally of a sterilized textile or cotton tissue. The surgical operation to be performed on the patient is carried out through an opening inside the covering sheet. All objects located above the covering sheet must therefore be sterilized whereas the objects located underneath the covering sheet or at a fairly wide spacing from the surgical event need not be sterile or at least not freed from germs by 100%.
Any manual direct operation or control of electric instruments located in the non-sterile area is therefore impossible for the surgeon for reasons of sterility
Pedal-operable control units disposed underneath an operating table, which provide for the surgeon a possibility to generate appropriate control signals via pedal contact switches or similar switching mechanisms, constitute a practical self-suggesting operating possibility for the surgeon. Such switch units for pedal operation present, however, fundamental disadvantages, specifically since they are not in the surgeon""s range of view. When certain electric instruments used to assist the operation should not only be switched on and off but also be operated individually, such as changes of the sense of rotation of a rotational drive or when the rotational speed is to be varied, this requires a great number of pedal switches to be operated in different ways, whose operability becomes less and less easy to survey for the surgeon as the number increases.
Another possibility of operating electric instruments from the sterile area also in the non-sterile area is the application of remote controllers of the kind known also for controlling conventional TV sets. Such battery-operated control panels can be expediently operated by the surgeon by hand, provided that they are entirely sterilizable, and may be placed in the sterile area immediately within the range of vision of a surgeon. What is a disadvantage, however, is the operation from a battery that provides only limited power supply. When the power supply is exhausted exactly during performance of an operation on account of the limited battery capacity, the electric instruments important for the operation can no longer be used for the operation. A diligent and permanent servicing of such remote control panels is accordingly indispensable. In view of the communication technology, which is mostly based on infrared or ultrasonic waves, it is moreover necessary for trouble-free communication between the remote controller and the electric instrument to be controlled that an unrestricted viewing contact exists between the remote commander and the electric instrument to be controlled. Whenever there are obstacles along the path, for example, in the form of persons control is strongly impaired or even impossible.
The French publication FR 2 671 507 discloses a sample table for biomedical samples, which can be positioned in the x-y direction by means of a manual operating panel present in the non-sterile zone of the room.
U.S. Pat. No. 5,969,502 describes a joystick system including a ferromagnetic track ball adapted to be moved relative to two sensor elements. The sensor elements are now capable of detecting the movements of the track ball so that joystick control becomes possible. The known joystick system is, however, unsuitable for the sterile application in the surgery zone.
The present invention provides a device for application in the sterile area for controlling an electric instrument provided in the non-sterile area, with the sterile area being separated from the non-sterile area substantially by a sheet-like covering means, of the kind in which the aforementioned disadvantages of the solutions are known. In particular, the device is easy to operate and maintenance-free in particular. A surgeon should have the possibility to issue control commands to the electric instrument to be controlled by manual operation in the sterile area, without exposure to the risk of contamination originating from the non-sterile area.
In accordance with the invention, a device for the application in the sterile area for controlling an electric instrument provided in the non-sterile area, with the sterile area being separated from the non-sterile area substantially by a sheet-like covering means, is improved by the provision that at least one sensor responsive to a magnetic field is provided in the non-sterile area and a unit generating a magnetic field is provided in the sterile area. The sensor responsive to a magnetic field as well as the unit generating the magnetic field are separated from each other at least by the sheet-like covering means, with the unit responsive to the magnetic field being disposed relative to the sensor responsive to the magnetic field being disposed in such a way that a variation in terms of space and/or time of the magnetic field created by the unit generating the magnetic field can be detected by the sensor responsive to the magnetic field and a sensor signal can be generated, and that finally a control unit is provided which generates a control signal for controlling the electric instrument in response to the sensor signal.
The device of the invention utilizes receives the control signals generated by the surgeon by means of magnetic interaction through the surgical towel or drape, that is from the sterile area into the non-sterile area, with the sheet-like covering means, i.e. the surgical sheet present in any operation, becoming part of the device as such.
In the simplest embodiment of the inventive device, according to the invention a permanent magnet is provided in the sterile area, which can be manually operated by the surgeon and must therefore be realized in a sterilizable form. A Hall sensor or a similar sensor responsive to a magnetic field, which detects variations in the magnetic field, generates sensor signals which are converted by means of an appropriately configured control unit into control signals for direct control of an electric instrument.
In order to establish a spatially fixed relationship between the unit generating the magnetic field and the sensor responsive to the magnetic field, which is located underneath the sheetlike covering means in the sterile zone, both components are integrated into appropriate molded bodies which are mobile relative to each other via appropriately configured contours in a spatially fixed relationship. For example, the unit generating the magnetic field, which is configured as permanent magnet or solenoid, is located in an operating element having a spherical configuration, which is separated by the sheet-like covering means and can be placed in an appropriately configured basic body having a semi-spherical counter-shape as well as the sensor responsive to the magnetic field. The two components can be moved relative to each other via the spherically shaped contact area between the operating element and the basic body.
The basic body, in which the sensor is responsive to the magnetic field, preferably comprises additionally an insert of ferromagnetic material or a counter-magnet selected in correspondence with the unit generating the magnetic field so that when the operating element is inserted into the basic body both components fit into each other in a self-centering manner. When the surgeon deflects the operating element in the sterile area from a centered position to the side, the sensor responsive to the magnetic field is capable of detecting the variation of the magnetic field, that derives from the deflection, which results in the generation of a corresponding control signal. When the surgeon releases grip on the operating element, the instrument returns automatically into an original position.
Moreover, an installation of the control device in accordance with the invention in the immediate vicinity of the operating area on the surgical towel or drape is easy to carry out. It is merely necessary to position the basic body under the sheet-like covering means and to insert the operating element into the basic body appropriately from the sterile side of the covering sheet, with the inserting operation being facilitated by the counter-magnet provided in the basic body and the permanent magnets disposed in the operating element.